In nature, the photolytic conversion of light to energy is a common mechanism for driving chemical reactions. As an example, photosynthesis utilizes energy derived from sunlight to promote key metabolic processes in plants, while exchanging oxygen for carbon dioxide. The purpose of the proposed research is to apply these physical principals to create an artificial system, composed of durable biomimetic materials, designed to replicate normal respiratory function. Despite vast improvements across the spectrum of health care in the past 20 years, there have been few substantial improvements in the care of patients with end- stage lung disease. While the death rate for most major diseases has decreased significantly, the rate of death related to chronic lung disease has actually increased during this period. As a result there has long been interest in the development of technology to replace severely diseased lungs. Since the proposed technology generates oxygen directly from the water content of whole blood, it avoids the need for gas-to- liquid diffusion membranes, pressurized gas, and gas cylinders, while retaining the full benefit of the red blood cell's ability to rapidly capture and transport dissolved oxygen. Our preliminary data has demonstrated the capacity to carry out photocatalytic respiration in blood flowing through a microchannel system, which is structurally and functionally similar to pulmonary capillaries. The overall goal of this proposal is build on this preliminary experience in order to develop a microfluidic scale device capable of carrying out artificial respiration powered by photocatalysis. Accordingly, our Specific Aims include the following: Specific Aim 1: Develop a photolytically active 2D microfludic device. Specific Aim 2: Develop metal oxide thin films with enhanced dissolved oxygen flux from the photocatalyst and reduced by-product carbon dioxide. Specific Aim 3: Determine basic biocompatibility of the microfluidic capillary system and photoactive components. It is anticipated that the successful implementation of this device in the clinical arena will have significant impact on the morbidity, mortality, and quality of life for the large number of children and adults with respiratory failure, as well as establishing an innovative realm of biomedical technology.